1. Field of the Invention
The present invention relates to an water-absorbing pad whereby to improve the absorbency of an water-absorbing product such as a diaper or a urine-receiving pad; an water-absorbing product using this water-absorbing pad; and to a method for washing a diaper or other water-absorbing products using the water-absorbing pad.
2. Description of the Related Art
Generally, a diaper for infants, the sick, and elderly people is composed of a cloth diaper and a diaper cover which is put thereon as a set. Particularly, in the case of an adult wearer, several cloth diapers (for example, three diapers) are often used in layers thereby to improve the absorbency.
Such diaper has the drawback that the excrement stays between the cloth diaper and the wearer""s skin and tends cause skin troubles (diaper rash). In addition, if several layers of cloth diapers are used, the diaper will be uncomfortable to wear, for the cloth diapers or the cloth diapers and the diaper cover are dislocated, etc.
The absorbency of the cloth diaper itself can be raised by weaving a cloth in such a manner that the fibers are slackened as loose as possible so that moisture is held therebetween. However, for example, even if a cloth is woven in the manner as described above, the cloth diaper is still required to be made bigger and heavier thereby to ensure an absorbency sufficient for use by an adult, and a diaper using a set of three cloth diapers each weighing, in a dried condition, as heavy as 220 g or so will be quite heavy.
On the other hand, in recent years, paper diapers improved in water absorption and retaining performance through the use of an water-absorbing polymer have come to be popularly employed. These paper diapers, though light, can ensure a sufficient absorbency and have the advantage that, due to their high water retaining performance, they hardly cause skin troubles.
However, paper diapers are generally expensive, and their being disposable presents the problem of waste.
Accordingly, an object of the present invention is to provide an water-absorbing pad with which to improve the absorbency and water-retaining capacity of a product such as diapers and make the product reusable by enabling it to be easily washable. Another object of the present invention is to provide an water-absorbing product or diaper using such water-absorbing pad, and a method for washing these products.
For achieving the objects mentioned above, in the present invention, an water-absorbing pad is constituted of an water-absorbing polymer which is dispersed, dissolved or melted in an electrolytic aqueous solution (e.g., a salt solution, a sodium hypochlorite aqueous solution, a calcium chloride aqueous solution) or an water-absorbing polymer crosslinks of which are broken in an electrolytic aqueous solution (e.g., a crosslinked polyacrylate-type resin or crosslinked polystarch acrylate-type resin) retained by, for example, being wrapped up in a water soluble material such as a water soluble sheet.
The water-absorbing pad is interposed between sheets of cloth or other materials for such water-absorbing products as diapers or urine-receiving pads. Since the absorbency and water-retaining capacity of the water-absorbing product are satisfactorily ensured through the use of this water-absorbing pad, a high absorbency is not required of the material of the product and therefore a thin and light-weight material can be used, enabling a reduction in the weight of the product as a whole. In the case of a conventional diaper, it is necessary to wrap one diaper constituting a set of three diapers around the waist of the wearer in order to prevent the leakage of urine or other fluids, but the diaper of the present invention eliminates the necessity for wrapping a cloth diaper around the waist like that, consequently making diaper change easier.
Moreover, through the use of a sheet of such a material as to allow moisture (e.g., urine) to easily permeate from its surface-side to the water-absorbing pad-side but hardly allow the reverse as at least one of the sheets between which the water-absorbing pad is interposed (e.g., the skin-side sheet), the moisture absorbed into the pad is prevented from flowing back, releasing the wearer from unpleasantness or skin troubles.
By washing a used water-absorbing product with an electrolytic aqueous solution such as a salt solution in an ordinary manner with the water-absorbing pad incorporated therein, the water-absorbing pad is dissolved, leaving no garbage behind, which not only enables the water used for washing to be discharged without any special sewage treatment but makes it possible to reuse the water-absorbing product.
Even if the water soluble sheet is dissolved when the water-absorbing pad absorbs water, since the pad has been interposed between the sheets, the risk of the remaining water-absorbing polymer leaking out of the product is low. From the viewpoint of complete dispersion, dissolution or melting, or breaking of the crosslinks of the water-absorbing polymer upon washing, dissolution of the water soluble sheet upon water uptake is rather favorable than not.
Moreover, a set of diaper sheets between which the water-absorbing pad is interposed is made detachable from the diaper cover. Thereby, not only does the resulting diaper become easier to wear because of the set of diaper sheets (and the water-absorbing pad interposed therebetween) integrally attached to the cover, but also in the case where the set of diaper sheets is stained or damaged to uselessness, it is made possible to reuse the diaper cover together with a new set of diaper sheets.
Further, the necessity for adding an electrolytic substance to washing water every time the water-absorbing product is washed can be eliminated by the following measures. That is, by impregnating the water-absorbing pad with an electrolytic substance, by incorporating an electrolytic substance or electrolytic aqueous solution into a glue or adhesive to be used for gluing the water soluble sheet, or by using a detergent containing a suitable amount of an electrolytic substance.